Personal assistant modules are software processes installed on computing devices such as smart phones, tablets, vehicle navigation systems, and smart watches to provide user-friendly interfaces for users to issue natural language commands. Users often issue natural language commands using their voices, but personal assistant modules may respond to other modalities as well, such as various forms of textual input. Existing personal assistant modules may lack sufficient intelligence to recall a user's previous declarations and/or preferences. Consequently, if a user issues an ambiguous declaration (e.g., request, statement, command) that can be potentially responded to in multiple ways, the personal assistant module may need to solicit additional information from the user to determine how to proceed. Suppose a user speaks the words “call Bob” into her phone, but there are multiple contacts in the user's phonebook that match the name “Bob.” A personal assistant module operating on the user's phone may ask which Bob the user meant and/or whether to dial Bob's home or work phone. Or, suppose another user speaks the words “remind me to pick up groceries tomorrow” into his smart watch. A personal assistant module operating on the user's smart watch—or on a smart phone in communication with the smart watch—may ask which application (e.g., calendar, task list, social networking application) the user wishes to use to set the reminder.